Sprint took no chances for its WiMAX XOHM celebration event in Baltimore.
The company deployed a supplemental "cell site on wheels" - or COW - on top of a parking garage next to the event to ensure WiMAX coverage was rock-solid. The COW is a glorified trailer containing equipment racks and an extendable mast to elevate antennas to the proper height.
COWs are used to provide supplemental coverage for larger events -- you see a lot of them in Las Vegas for the Consumer Electronics Show and other large trade shows -- and at disasters and other emergencies when the primary coverage has been clobbered (Think Hurricane and downed cellular tower).
More pictures of the COW and its equipment can be found at the full slideshow here.